1. Field of the Invention
The present invention is directed to a technique for high repetition rate operation of a carrier-injected avalanche device and, specifically, to a biasing technique for a carrier injected avalanche device which generates a current pulse in response to the injection carriers, to drive an injection laser connected in series with the avalanche device.
2. Description of the Prior Art
U.S. Pat. No. 3,855,605 issued Dec. 17, 1974 to H. Kawamoto is directed to a carrier injected avalanche device. As described therein, the carrier injected avalanche device comprises a two terminal avalanche diode having at least first, second and third crystalline semiconductor layers. The first and third layers are of a highly doped semiconductor material and form junctions with the second layer which is of a lightly doped semiconductor material. The type of doping in the second layer is the same as that of the third layer but different from that of the first layer. A fourth layer may be used if desired, forming an additional junction with the first layer and has the same type of doping as the second layer. In operation, a reverse bias signal having a magnitude less than a predetermined threshold level, is applied across the avalanche diode terminal. The bias signal is chosen to be insufficient, in itself, to establish the critical magnitude of electric field within the device causing avalanche breakdown in the diode. However, the injection of external carriers into the second semiconductor layer increases the level of the electric field so as to cause avalanche breakdown to occur. As noted in that patent (U.S. Pat. No. 3,855,605) such a carrier injected avalanche device is capable of generating output voltage pulses having a duration of only about 5 nanoseconds.
Copending application Ser. No. 524,757 now U.S. Pat. No. 3,953,809 entitled "Nanosecond Modulation of Injection Laser," filed by the present inventors on Nov. 18, 1974 describes, in general, a pulse generator utilizing a carrier injected avalanche device such as described in the above-mentioned U.S. Pat. No. 3,855,605 to H. Kawamoto, and specifically, an injection laser modulator utilizing a carrier injected avalanche device.